Embodiments relate to radome technology and, more particularly, to radome technology which provides for frequency selectivity with reduced signal loss.
A radome is a structural, weatherproof enclosure typically provided to protect a sensor and/or antenna. The radome is constructed of material that minimally attenuates the electromagnetic signal transmitted or received by the antenna and/or sensor. More specifically, the radome is transparent to radar, radio, or infrared waves.
A multimode sensor (semi-active and/or passive infrared (“IR”) as well as millimeter-wave radar frequencies (“RF”)) generally includes a radome for protection from the environment as well as for band selectivity, such as a radome that can pass IR and some millimeter wavelength signals, and reject other millimeter wave and microwave signals. The radome should have very little effect on the signals that pass through it, while rejecting certain wavelengths (e.g., a particular band of RF signals) to reduce the radar cross section as well as reduce electromagnetic interference reaching the antenna and thus the circuitry of the senor. Additionally, the interior of the body and the sensor circuitry housed in the body is also able to be disrupted by electromagnetic interference (“EMI”), Frequencies near the operating RF are excluded from the normal signal path, just past the antenna, using filters.
Known radomes include those having frequency selective slots which allow the radar signal to pass through while excluding other frequencies. However, this type of radome does not allow for the transmission of IR signals. Another known radome allows both IR and millimeter wave radar signals to be transmitted. To make this type of radome frequency selective, wire grids are inserted between two layers of dielectric material, and the dielectric materials are in direct contact with each other. The surfaces of the two dielectrics that must touch each other are difficult to machine to the tolerance necessary so as not to allow small spaces to appear between the two layers. These small spaces can also cause an interference effect which can spoil the JR image. This radome type is also expensive to manufacture, and the wire grids are known to block some of the IR and millimeter wave signals which increases the signal loss of the radome.
Though current radome technology allows for radomes to be used with multimode sensors Which have semi-active and passive infrared as well as millimeter-wave radar, manufacturers and users of systems utilizing such multimode sensors would benefit from a radome which reduces signal loss attributed to structure of the radome while also reducing costs associated with the manufacture of such radomes.